The emergence of human Powassan virus infection in North America

Powassan virus (POWV) is a tickborne flavivirus discovered in Ontario, Canada in 1958 that causes long-term neurological sequelae in about half the reported cases and death in a little more than 10 % of cases. The incidence of POWV disease is rising in the United States but there is limited understanding of the scope and causes of recent changes in POWV epidemiology. We focus on quantifying the increase in human POWV disease incidence and infection prevalence in the United States. We also examine differences in the frequency of symptomatic cases and asymptomatic or mildly symptomatic cases, as well as limitations in national and state surveillance for POWV infection. We searched SCOPUS for all articles containing original POWV prevalence research, case studies, or literature reviews published in English. Case studies were supplemented by Morbidity and Mortality Weekly Report POWV data from the Centers for Disease Control and Prevention (CDC) and surveillance information from state health department websites. An increase in the number of POWV cases has been reported in the United States over the past 50 yr, and the geographic range of human POWV cases has expanded. The age distribution of symptomatic POWV cases has shifted, with significantly more individuals over 40 yr old being diagnosed after 1998. The emergence of POWV is due in large part to: (i) a change in transmission of POWV from a vector that rarely bites people (Ixodes cookei) to a new vector that often bites people (Ixodes scapularis) and has expanded its geographic range, (ii) enhanced surveillance efforts for arboviruses, and (iii) a greater awareness of POWV infection.     

Enhanced surveillance of tetanus toxoid,reduced diphtheria toxoid,and acellular pertussis (Tdap) vaccines in pregnancy in the Vaccine Adverse Event Reporting System (VAERS), 2011–2015

BackgroundIn October 2011, the Advisory Committee on Immunization Practices (ACIP) issued updated recommendations that all pregnant women routinely receive a dose of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine.ObjectivesWe characterized reports to the Vaccine Adverse Event Reporting System (VAERS) in pregnant women who received Tdap after this updated recommendation (2011–2015) and compared the pattern of adverse events (AEs) with the period before the updated recommendation (2005–2010).MethodsWe searched the VAERS database for reports of AEs in pregnant women who received Tdap vaccine after the routine recommendation (11/01/2011–6/30/2015) and compared it to published data before the routine Tdap recommendation (01/01/2005–06/30/2010). We conducted clinical review of reports and available medical records. The clinical pattern of reports in the post-recommendation period was compared with the pattern before the routine Tdap recommendation.ResultsWe found 392 reports of Tdap vaccination after the routine recommendation. One neonatal death but no maternal deaths were reported. No maternal or neonatal deaths were reported before the recommendation. We observed an increase in proportion of reports for stillbirths (1.5–2.8%) and injection site reactions/arm pain (4.5–11.9%) after the recommendation compared to the period before the routine recommendation for Tdap during pregnancy. We noted a decrease in reports of spontaneous abortion (16.7–1%). After the 2011 Tdap recommendation, in most reports, vaccination (79%) occurred during the third trimester compared to 4% before the 2011 Tdap recommendation. Twenty-six reports of repeat Tdap were received in VAERS; 13 did not report an AE. One medical facility accounted for 27% of all submitted reports.ConclusionsNo new or unexpected vaccine AEs were noted among pregnant women who received Tdap after routine recommendations for maternal Tdap vaccination. Changes in reporting patterns would be expected, given the broader use of Tdap in pregnant women in the third trimester.     

Predictors of tetanus,diphtheria, acellular pertussis and influenza vaccination during pregnancy among full-term deliveries in a medically underserved population

ObjectiveTo evaluate predictors of vaccination among women who received tetanus, diphtheria, and acellular pertussis vaccination (Tdap), influenza vaccination, and Tdap and influenza vaccinations.Study DesignIn a retrospective cohort study of all full-term (≥37 weeks gestation) deliveries between July 1, 2016 and June 30, 2018 at a single, safety-net institution, we used multinomial logistic regression models to compare predictors of vaccination among women who received Tdap only, influenza only, and both Tdap and influenza vaccines.ResultsAmong 3132 full-term deliveries, women were primarily non-Hispanic black (67.5%), between the ages of 21–34 (65.3%), and multiparous (76.0%). The rates of only influenza or Tdap vaccination were 10.3% and 21.6%, respectively; 43.3% of women received both vaccines, and 24.9% of women did not receive either vaccine. In the adjusted models, Hispanic ethnicity was positively associated with receipt of all types of vaccination and non-Spanish language interpreter use was positively associated with receipt of Tdap vaccination and Tdap and influenza vaccination. A parity of greater than three and inadequate and unknown prenatal care adequacy were negative predictors of all types of vaccination. Pre-existing hypertension was negatively associated with Tdap vaccination, and HIV-positive status was negatively associated with influenza vaccination and Tdap and influenza vaccination.ConclusionCompared to the national rate of both Tdap and influenza vaccination (32.8%), a higher proportion of women received both vaccines in our study population. Vaccine uptake may be affected by race/ethnicity, use of interpreter services, parity, pre-existing comorbidities, and prenatal care adequacy. The lower rate of influenza vaccination compared to Tdap vaccination suggests that other factors, such as vaccine hesitancy and mistrust, may be differentially impacting influenza vaccination uptake in our predominantly minority population. Future provider and public health approaches to vaccine promotion should incorporate culturally appropriate strategies that address vaccine-related beliefs and misconceptions.     

Durability of humoral immune responses to rubella following MMR vaccination

BackgroundWhile administration of the measles-mumps-rubella (MMR-II®) vaccine has been effective at preventing rubella infection in the United States, the durability of humoral immunity to the rubella component of MMR vaccine has not been widely studied among older adolescents and adults.MethodsIn this longitudinal study, we sought to assess the durability of rubella virus (RV)-specific humoral immunity in a healthy population (n = 98) of adolescents and young adults at two timepoints: ~7 and ~17 years after two doses of MMR-II® vaccination. Levels of circulating antibodies specific to RV were measured by ELISA and an immune-colorimetric neutralization assay. RV-specific memory B cell responses were also measured by ELISpot.ResultsRubella-specific IgG antibody titers, neutralizing antibody titers, and memory B cell responses declined with increasing time since vaccination; however, these decreases were relatively moderate. Memory B cell responses exhibited a greater decline in men compared to women.ConclusionsCollectively, rubella-specific humoral immunity declines following vaccination, although subjects’ antibody titers remain well above the currently recognized threshold for protective immunity. Clinical correlates of protection based on neutralizing antibody titer and memory B cell ELISpot response should be defined.     

Longitudinal analysis of the in vitro activity of ceftazidime-avibactam vs. Pseudomonas aeruginosa, 2012–2016

The in vitro activities of ceftazidime-avibactam and comparator agents were analyzed against 14,330 isolates of Pseudomonas aeruginosa from 188 centers distributed globally (except North America) from 2012 (2014 for colistin) to 2016 as part of the International Network for Optimal Resistance Monitoring (INFORM) global surveillance program. Susceptibility testing used in-house prepared broth microdilution panels following CLSI guidelines. Multiplex PCR assays identified the presence of β-lactamases. Ceftazidime-avibactam (MIC₉₀ 8 mg/L; 91.5% susceptibility) and colistin (N = 11,032; MIC₉₀ 2 mg/L, 96.2%) were the 2 most active agents. Susceptibility of multidrug-resistant isolates (N = 3770, 26.3%) was ≤54.4% to all agents except colistin (N = 2956; 95.2% susceptible) and ceftazidime-avibactam (68.2%). Metallo-β-lactamase–positive isolates (N = 621, 4.3%) were not susceptible to any agents except colistin (N = 504; 98.2% susceptible). Novel therapeutic options are needed for infections caused by P. aeruginosa–resistant phenotypes.